NEW ECHIUROID AND SIPUNCULOID WORMS—FISHER 357 
Larvae.—A considerable number of Sipunculus (Pelagosphaera) 
larvae were taken in tow nets by the Bache, between January 28 
and March 21, 1914, in an area between the Straits of Florida, Ber- 
muda, and the Gulf Stream off Cape Hatteras, at depths of 150 meters 
to surface. These larvae, in formaldehyde, are nearly transparent, 
are usually ellipsoidal but sometimes subspherical, and vary in size 
from 3 by 2.25 mm. to 6 by 4mm. With one exception they are in 
about the same stage of development (fig. 54). 
All the specimens have the introvert contracted. They are covered 
by an excessively thin iridescent cuticle, beneath which 56 longitu- 
dinal muscle bands extend from pole to pole. These bands are trans- 
lucent and about twice as broad as the transparent skin between. 
Only one specimen was found to have developed visible ring muscles. 
These occur in the area posterior to anus, while the region in front is 
a little lengthened and constricted so that the larva has a fat vase- 
shaped form. There is no difference in the internal organs. 
The reason for suspecting that these larvae may be Sipunculus 
polymyoius is, of course, the number of muscle bands. 
The coelom is very spacious and filled with fluid. In addition to 
the four retractors there are eight very delicate strands arising in 
front of the insertion of the retractors and shown only for the left 
side in figure 54. The ventral retractor is attached between longi- 
tudinal muscles 5 and 6 or 6 and 7; the dorsal between 20 and 21 
or 21 and 22; The strand that meets the body wall behind the dorsal 
retractor is attached between 21 and 22 or 22 and 23. The small 
nephridium opens between 11 and 12, varying to 13 and 14. The 
nerve cord at its anterior end, where it is free from close contact with 
the body wall, is already characteristically sipunculoid. The brain is 
well hidden. 
Harold Heath (1910) has described and figured a quite different 
Pelagosphaera trom Monterey Bay, Calif., which is undoubtedly a 
sipunculoid. It is spherical, 2.5 to 3.5 mm. in diameter. 
Tasie 1.—Localities at which larvae of Sipunculus polymyotus were taken by the 
Bache 1914 
Date eee i Position Depth | Salinity forenas 
Meters | Percent Gt 
Jans 28 12154. 13) BOIGE: |: R5°D74 ING WSCA Wie. ee EE es 110-0 36. 38 21. 50 
CCR! ea TR TTA BS ED ST lS 11, a RT eS 150-0 36. 44 19. 30 
Jan.3land Feb.1-. 10169" | 32°20! IN. j FIP 20 Weer 28s ced ee ee 50-0 36. 44 18. 95 
Reb, Ge+er 2 45 EOETB if dee SOtNe, 60°48 WWead ooh on So eee 50-0 36. 44 19. 20 
Reb, LA M8 2. HOSTS) Secret IN O452L CNV peere oS eho 50-0 36. 42 18. 80 
Bep.'262 2t\7 ee LO#96. | 20200! 'N.5°76°23’ W428 So 2 file Peto 100-0 36. 49 21.70 
Mar, 18242-4_-2. HOZ00. 289820 N's SLSASE TW Seetie ccs go 8 ale et be 75-0 35. 93 24. 78 
Marg2ts S221 6 LODO (Al 27 2SaLIN a Oo OL) WV 22 nae Ee EP ee 100-0 36.7 23. 70 
